1. Field of the Invention
The present invention relates to a pneumatic radial tire for aircraft such as passenger jet airplanes.
2. Description of the Prior Art
Various kinds of radial tires exclusive for aircraft are used for aircraft such as passenger jet airplanes. In some of these tires, the same rubber is used for the sidewall rubber and rubber chafer. If the same rubber as used for the sidewall is used for the rubber chafer, since the rubber is soft, there is a possibility that air cells may occur in the rubber and the rubber chafer may blow-out under tire service conditions of high heat generation. Also, the rubber chafer may be worn out by chafing with the wheel rim after long distance tire service. On the other hand, if the same rubber as used for the chafer is used for the sidewall, there is the possibility that so-called ozone cracks may occur at the sidewall.
Since there occurs considerable load concentration at bead portions when large weight is loaded on a radial tire having flexible sidewalls, the modulus of 2nd stiffener rubber (2nd stiffeners provided at the bead portions and extending along the axially outer surface of the carcass) at 100% elongation is sometimes made larger than the modulus of the chafer rubber at 100% elongation so as to increase bending (flexural) rigidity of the bead portions. In this case, since the 2nd stiffener rubber is too rigid, there is the possibility that the 2nd stiffener may blow-out under tire service conditions of high heat generation. Also, the 2nd stiffener may be separated after long distance tire service.
An object of the present invention is to provide a pneumatic tire for aircraft which prevents or at least reduces such damage as rim chafing, blow-out and separation.